The present invention relates to a planted surface moisture control system. More particularly, the present invention relates to an improved system for automatically controlling drainage, irrigation, and subirrigation of a planted surface, such as an athletic field, to maintain the moisture level of the planted surface within a predetermined desired range.
The present invention is an improvement over the planted surface conditioning system described in U.S. Pat. No. 3,908,385 which is owned by the assignee of the present application. The specification of U.S. Pat. No. 3,908,385 is incorporated into the present application by reference.
Outdoor athletic fields are typically constructed by grading the top soil at the proposed site to facilitate surface water run-off. A typical athletic field may be crowned about 16-24 inches in a center portion of the field. Despite being crowned, athletic fields often become wet and muddy under rainy conditions. In addition, when the athletic field is dry, the surface of the field can become very hard. Both of these field conditions tend to promote injuries to athletes using the field.
One solution for avoiding muddy field conditions is to use artificial turf on the field. The wide-spread use of artificial turf has been a costly solution to eliminate muddy field conditions. Artificial turf has also caused many injuries to players. Therefore, many stadiums which have artificial turf fields are now switching to natural grass.
It is known to provide systems for automatically controlling the range of soil moisture in a planted surface. U.S. Pat. No. 3,908,385 discloses a system which includes vacuum pumps for assisting drainage of water from the field through a series of collector drains. In this system, vacuum pumps are located underground in concrete pump pits adjacent to the athletic field. The vacuum pumps provide suction to collector drains to draw air and liquid from the turf through the collector drains and into an outlet drain. The concrete pump pits are often expensive to build, and the concrete pits must comply with rather stringent building regulations which vary for each community in which the system is installed. In addition, installing underground vacuum pumps is expensive and often requires that existing sections of a stadium be removed in order to install the underground vacuum pumps. See U.S. Pat. No. 3,908,385 for a further description of a conventional planted surface moisture control system.
The present invention provides a natural grass athletic field or other planted surface which can be quickly drained to avoid wet or muddy conditions on the field. This permits the field to be used for scheduled athletic events despite relatively heavy rainfall. During dry periods, the present invention automatically waters the field to prevent the field from becoming dry and hard.
An object of the present invention is to incorporate an improved suction system into a moisture control system, to increase the speed of construction, to reduce costs, and to increase the efficiency of operation of the system over conventional moisture control systems. The present invention includes a sealed water collection tank located under and adjacent to an athletic field and an elevated air evacuation tank located at a remote location spaced apart from the collection tank. This eliminates the need to place the vacuum pump underneath the stands, which may require reconstruction of portions of the stadium.
According to one aspect of the present invention, a system is provided for controlling the moisture content of a planted surface. The system includes a plurality of drain conduits located beneath the planted surface for collecting liquid from the planted surface. The system also includes a sealed collection tank coupled to the plurality of drain conduits. The collection tank is located beneath the planted surface to collect liquid passing through the plurality of drain conduits. The system also includes a vacuum pump coupled to the collection tank for removing air from the collection tank to provide a suction force in the collection tank and in the plurality of drain conduits to draw liquid from the planted surface through the plurality of drain conduits and into the collection tank.
According to another aspect of the invention, an elevated air tank is coupled between the vacuum pump and the collection tank. The elevated air tank is located at a remote location spaced apart from the collection tank. The collection tank provides a large vacuum chamber to assist drawing air and water from the planted surface into the plurality of drain conduits. The vacuum pumps remove air from the air tank which causes the suction force on the air tank, in the collecting tank, and in the plurality of drain conduits.
In a preferred embodiment, the collection tank is a sealed plastic tank formed to include a plurality of inlets coupled to the plurality of drain conduits so that a mixture of liquid and air passing through the plurality of drain conduits enters the collection tank through the plurality of inlets. The collection tank is formed to include an air outlet coupled to the air tank to evacuate air from the collection tank.
According to yet another aspect of the invention, a waste pit is located adjacent to the collection tank beneath the planted surface, and a pump is located in the collection tank for pumping liquid from the collection tank into the waste pit. An outlet drain is coupled to the waste pit for removing liquid from the waste pit. A drain outlet pipe is also coupled to the collection tank to drain liquid from the collection tank into the waste pit upon failure of the pump. A valve is coupled to the drain outlet pipe for opening and closing the drain outlet pipe.
A waterproof barrier is located beneath the plurality of drain conduits. A plurality of submains extend through the barrier to couple the plurality of drain conduits to the collection tank. An upwardly extending pipe is coupled to an end of the drain outlet pipe. The upwardly extending pipe has a predetermined height so that a predetermined amount of water is retained above the barrier. Excess water above the predetermined amount overflows from the upwardly extending pipe and into the waste pit. This permits maximum conservation of water during dry periods.
According to still another aspect of the present invention, a plurality of moisture sensors are located beneath the planted surface. The moisture sensors generate an output signal indicative of the moisture content of the soil. The moisture control system includes means for automatically enabling the vacuum pump in response to the output signal from the moisture sensors when the moisture content of the soil rises above a predetermined level.
According to a further aspect of the invention, a water inlet pipe is coupled to the collection tank and a valve is coupled to the water inlet pipe for selectively supplying water to the water inlet pipe to add water to the collection tank. Adding water to the collection tank forces water into the plurality of drain conduits located beneath the planted surface to subirrigate the planted surface. The system of the present invention includes means for automatically opening the valve to supply water to the water inlet pipe to add water to the collection tank in response to the output signal from the moisture sensors when the moisture content of the soil falls below a predetermined level. By removing water when the planted surface is too wet and adding water when the planted surface is too dry, the moisture control system of the present invention automatically maintains the moisture level of the planted surface within a predetermined moisture range.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of a preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.